This invention relates to a chip composite electronic component having a capacitor and a resistor of the thick-film type formed on a chip insulator substrate, and a method of manufacturing the same.
The composite component of this type, as shown in FIGS. 11 and 12, is structured by a capacitor 8' and a resistor 10' formed on a ceramic insulator substrate 1'. That is, on the surface of the substrate 1'. opposite end electrodes 2', 3' are provided for external electrical connection. Between these end electrodes 2', 3' is provided continuous connection of a capacitor lower electrode 4a' and a resistor electrode 4b'. The capacitor lower electrode 4a' has a dielectric film 5' provided in a manner covering the same electrode 4a'. A capacitor upper electrode 6' is provided overlying the dielectric film 5' such that one end of the same electrode 6' is electrically connected to one end electrode 2', By covering these elements with a first glass layer 7', a thick-film capacitor is provided Meanwhile, a resistance element 9' is provided to bridge between the resistance electrode 4b' and the other end electrode 3', constituting a thick-film resistor 10' The thick-film capacitor 8' and the thick-film resistor 10' are covered at their entirety by a second glass layer 11' and further a synthetic resin protective coating 12'. Furthermore, side electrodes 13', 14' are provided at opposite end faces of the substrate 1'.
The composite component constructed as above is being manufactured by a method as follows.
(i) First, as shown in FIG. 13, on an insulator substrate 1' are formed respective end electrodes 2', 3', a capacitor lower electrode 4a' and a resistor electrode 4b' and a pad electrode 4c' continuous therebetween. Thereafter a dielectric film 5' is formed covering the capacitor lower electrode 4a'. PA1 (ii) As shown in FIG. 14, a capacitor upper electrode 6' and a first glass layer 7' covering the same are formed, and then a resistance element 9' is formed. PA1 (iii) As shown in FIG. 15, a second glass layer 11' is formed so as to cover the first glass layer 7' and the resistance element 9' except for the area of the pad electrode 4c'. Thereafter, a trimming groove 9a' is formed by irradiation of a laser beam to provide a predetermined resistance value to the resistance element 9' while measuring the resistance value by supplying an electric current through the resistance element 9' with electricity-supply probes A, B respectively contacted with the other end electrode 3' and the pad electrode 4c'. PA1 (iv) As shown in FIG. 16, a synthetic-resin protective coating 12' is formed over almost entire top surface of the substrate 1' Then side electrodes 13' 14' are formed at opposite end face-of the substrate 1'. PA1 an insulator substrate; PA1 a pair of end electrodes formed on a surface of the substrate at opposite end portions thereof; PA1 an intermediate electrode formed at a location between the end electrodes on the surface of the substrate, the intermediate electrode including a lower electrode, a resistor electrode and a pad electrode formed continuous therebetween; PA1 another element formed on the lower electrode so an to be electrically connected between the lower electrode and one of the end electrodes; PA1 a resistance element formed between the other of the end electrodes and the resistor electrode; PA1 a glass layer formed to cover the other element, the resistance element and the pad electrode; and PA1 a protective layer of a synthetic resin formed to cover the entire surface of the glass layer and part of each the end electrode. PA1 a step of forming a pair of end electrodes on a surface of an insulator substrate at opposite end portions thereof; PA1 a step of forming an intermediate electrode at a location between the end electrodes on the surface of the substrate so that the intermediate electrode includes a lower electrodes a resistor electrode and a pad electrode formed continuous therebetween; PA1 a step of forming an another element so as to be electrically connected between one of the end electrodes and the lower electrodee; PA1 a step of forming a resistance element between the other of the end electrodes and the resistor electrode; PA1 a step of forming a trimming groove in the resistance element to adjust the resistance value of the resistance element while measuring the resistance value with probes respectively contacted with the pad electrode and the other end electrode; PA1 a step of forming a glass layer to cover the other element, the resistance element and the pad electrode; and PA1 a step of forming a protective layer of a synthetic resin to cover the entire of the glass layer and part of each the end electrode.
In the conventional composite component, the second glass layer 11' is formed to cover the first glass layer 7' and the resistance element 9' except for the area of the pad electrode 4c'. In this state, a trimming groove 9a' is formed by a laser beam to trimming-adjust the resistance value of the resistance element 9' to a predetermined value while measuring the resistance with electricity-supply probes A, B respectively contacted with the other end electrode 3' and the pad electrode 4c'. Thereafter the surface of the substrate 1' is coated by the synthetic-resin protective coat 12'.
The conventional structure uses a synthetic resin of protective coat 12' so that there is an advantage that weight reduction is readily available as compared with the glass coating structure, with reduced cost. Furthermore, externally applied impact to the composite component is relieved by the synthetic-resin coating 12'.
On the contrary, the pad electrode 4c' for trimming-adjusting the resistance value is covered solely by the synthetic-resin coating 12'. However, if the synthetic-resin coat 12' deteriorates due to exposure to a high temperature (approximately 350.degree. C.) when the composite component is solder-mounted onto a circuit board, there often encounters a problem that moisture intrudes to the inside of the protective coat 12' to induce short circuit between the pad electrode 4c' and the other end electrode 3'.